The present invention relates to apparatus and methods for sealing envelopes and may form part of apparatus for inserting documents into envelopes.
Envelope inserting apparatus is well known and involves inserting paper documents into a waiting envelope that has had its front and rear panels spread apart to receive the insert material. In the inserting station, the envelope arrives first and is typically opened by a combination of devices which may include bending rolls and hold-down fingers. The contents to be inserted then arrive through a second path and are driven into the envelope. Typically, the last part of the inserting motion is accomplished ballistically for about 0.5° to 0.8° using the kinetic energy of the inserts. Reliability problems exist with this system because the envelope does not always open sufficiently, and, due to the bent nature of the envelope, drag is created on the insert material preventing it from reaching the bottom of the envelope.
Apparatus which positively opens the envelope and holds the envelope open, thereby greatly reducing the amount of drag on the insert material and assuring that the insert material is reliably inserted into the waiting envelope, is known from the present applicants' European Patent Application 0 785 092A. In this apparatus, a waiting envelope is supported in a substantially horizontal plane with its back panel situated above its front panel and the envelope flap in its open position and substantially in the plane of the front panel. A pair of hold-down fingers presses the envelope flap from above against the inboard ends of respective pivotable paddles having an interior leg and an exterior leg angled out of the plane of the interior leg, to cause the flap to be bowed downwardly. This causes the rear panel to “pop” upwardly, thereby opening the envelope ready for an insert or insert collation to be inserted.
A succession of documents is fed, collated, optionally stapled, folded, and then inserted into the waiting envelope. The stuffed envelope is then moistened along its gummed flap, and sealed at a sealing station. However, as the number of inserts increases, there is an increasing tendency for the sealed envelope to burst open again. This places a constraint on the number of possible inserts.
It is an aim of the present invention to provide an envelope sealing apparatus whose operation is improved in this respect.